Radiant-energy-opaque fabric



Patented Dec. 30, 1952 2,623,549 RADIANTENERGYOPAQUE FABRIC Vincent W.

to Research Corporation, New

Archer, Charlottesville, Va., assignor York, N. Y., a

corporation of New York No Drawing.

Application April 21, 1949,

Serial No. 88,915

11 Claims. (01 129-420 The present invention in general relates to wovenradiopaque fabrics, and more particularly to protective fabrics opaqueto radiant energy emissions comprising a flexible web of woven leadglass fibers or filaments.

A paramount problem occurring in activities associated with use of X-rayand radiant energy generators, is that of minimizing the quantity ofscattered radiation incident to the activity that may possibly reach thebodies of the technicians, attendants, and those required because of thenature of their duties to be exposed to the scattered radiation for longperiods of time.

For example, in the course of present day medical practice andprocedure, technicians, attendants, and doctors are often required toremain in an enclosure in which X-rays are being generated for purposesof X-ray fluoroscope examination of the human body throughout asubstantial portion of the day. Many protective measures are generallyX-ray exposure. Normally, the X-ray generator used in such fluoroscopicexaminations is controlled to emit X-radiation over only a very shortfraction of the total time such operators and attendants are in thefluoroscopic examination room. Generally, protective shielding isprovided in the walls and about the generator to confine the emitted'X-radiation to a very small, highly directive area, and in many casesthe attendants and apparatus are encased in protective cells or housingsin which they remain throughout the major portion of the time that theX-ray generator is in operation. Notwithstanding this, large quantitiesof scattered X-radiation have been found to occur in even theseprotected areas.

Evidence of the seriousness of this problem is found in the fact thatthe percentage of occurrences or anemia and the number of fatalitiesfrom anemia among members of the medical profession are extremely highamong the group employed for any length of time in X-ray rooms. is amatter of fact, the medical profession now generally recognizes thatscattered X-radiation and'other radiant energy emission is probably oneof the principal causes of anemia.

Due to the tremendous increase in activity in various fields of atomicresearch, particularly those involving atomic bombardment by high energyparticles, isotopic investigations, and

other activities involving generation of emergent high energy radiationproducts, the problem of providing suitable protection for those engagedin such activities against scattered radiation is particularly acute.

taken as a precaution againstcost of such a protective conventionally,protection against such scattered radiations has been sought through theuse of protective barriers of considerable thickness, such as leadwalls, or concrete block impregnated with large quantities of lead orlead compounds. For example, the entire working area immediatelysurrounding the products from which such radiations may be emitted hasbeen encased in large lead or lead-concrete housings, and remote meansfor handling and controlling the products have been provided for theoperators, or the operators are confined to cells or protectiveenclosures of similar design and composition. Obviously such protectivemeans impose severe restriction upon the movement, freedom of activityof those engaged in such work, and the degree of control over theproduct. It is apparent, therefore, that there is a particular need forsome means by which such scattered radiant energy emissions can beeffectively excluded from those required to be in the vicinity of andexposed to the scattered emissions, while still permitting them to movefreely about the area and exercise a high degree of control over thework, particularly to permit substantial freedom of movement of the bodymembers of the workers.

The desirability of providing such protection in the form of protectiveclothing for the workers required to be exposed to such scatteredradiation should, therefore, be apparent, as such protective clothing,if maintained in a reasonably flexible and resilient state, would affordthe desired freedom of movement. Incorporation of some type of lead orother protective coating in the clothing, or similar protective insertsin the clothing, would render the clothing difficult to work in. Themore desirable solution to the problemwould appear, therefore, to be inthe provision of a protective fabric incorporating in the thread orfibers, or as an inherent and integral characteristic of the materialitself, the medium or composition opaque to such radiant energyemission. As the radiopaque element or medium should be incorporated inthreads or fibers suitable for ordinary spinning, plying and Weavingoperations on conventional textile machinery, coating of existingtextile fibers or threads with the radiopaque composition would seem tobe eliminated as a practical solution. This is because the knownradiopaque compositions are substantially brittle and unyielding innature, and would prevent the textile fibers from having the necessarycharacteristics to render them suitable for such spinning and weavingoperations. In order to prevent the fabric from being prohibitive tothose classes most in need of such protection, the components from whichthe fabric is to be produced must still be susceptible of theconventional mass production textile operations. The radiopaquecomposition or medium, therefore, must be incorporated in thecomposition of the textile thread or fiber itself, so that theprotective thread or fiber will retain the characteristics of uniformstrength throughout, high tensile strength, and be highly flexible andstretchable.

An object of the present invention is the provision of a protectivefabric opaque to radiant energy emissions.

Another object of the present invention is the provision of a protectivefabric opaque to radiant energy emissions, which is suificientlyflexible to permit substantially unrestricted freedom of movement whenfabricated into garments to be worn by persons exposed to such radiantenergy emission.

Another object of the present invention is the provision of a radiopaquewoven fabric formed of woven thread or fiber elements having a hightensile strength and the necessary characteristics of flexibility andstretchability necessary to permit spinning and weaving of the threadson conventional textile machinery.

Another object of the present inventionis the provision of a radiopaquewoven fabric formed of a Web of threads or fibers suitable forconventional textile operations and having a high lead con tent.

Another object of the present invention is the provision of a protectivewoven fabric opaque to radiant energy emissions comprising a flexibleweb of densely woven lead glass fibers suitable for fabrication intoprotective garments.

In the preferred embodiment of the present invention, a glass threadwhich has incorporated in its composition a material which isradiopaque, is spun and plied, by methods commonly known and used in thetextile arts, and woven into a web to form a fabric suitable to betailored into garments. The glass fiber from which the finished productis to be produced is formed by mechanical drawing of glass or the likein accordance with methods and with the use of apparatus known to theglass art and commonly employed in the production of spun glass, to formrelatively continuous threads of siliceous fibers. The production ofglass or siliceous fibers by the mechanical drawing processes has beencommonly employed for providing drawn glass fibers of sufficiently smalldiameter and high tensile strength and flexibility suitable for use inconnection with conventional textile spinning and weaving machinery forthe production of womens dresses and like garments.

The method conventionally employed in effecting this mechanical drawingof the glass into continuous uniform siliceous fibers comprises, ingeneral, the melting of a batch of lime glass or other glass compoundsin a receptacle. The receptacle is provided with a very small orificehaving a refractory ceramic bushing, or a metal bushing or thimbleprovided with a series of nipples of extremely small diameter of theorder of a few microns, and the molten glass is continuously drawnthrough such orifices into the atmosphere and cooled by means of coolair jets to provide the spun glass filament. These drawn filaments areWound about a continuously driven pulling means in the form of a drum orspindle in much the same manner that cotton or other textile fibers arewound.

Sizings or coating such as oil, wax, cellulose derivatives, resins,starches, fats, fatty acids and other suitable known substances may beapplied to the fibers by spraying or other means as they are beingcooled to reduce dis-continuities or fissures along the periphery of thefibers, thereby increasing the uniformity of size and strengththroughout the length of the fibers. Normally, series of transverselyspaced orifices or nipples are provided from which the molten glassfibers are drawn and the individual fibers combined after they have beencooled and before they reach the drum or spindle upon which they arebeing wound, to provide a single thread made up of several individualfilaments to permit a large number of individual filaments or threads tobe drawn from the orifices.

The multiplicity of spun glass fibers drawn from the thimble or orificeand wound onto the cylindrical drum or spindle may be further wound orplied into threads on conventional textile spinning and plying machines,or may be employed in the wound thread form in which they occur on thedrum or spindle, for weaving fabric webs on conventional textile looms.

In the production of the finished protective fabric the subject of theinstant application, the radiopaque substance or medium providingprotection against radiant energy emission is integrally incorporatedinto the composition of the glass thread by drawing the thread from aglass of very high lead content. This is accomplished by substitutingfor the conventional lime glass or similar glass compositions formingthe supply body or batch of molten glass, a lead glass of the typenormally employed in the production of fine crystal and the likecomprising a potash-leadsilicate combination. Specifically the glassmaking up the molten supply body from which the glass fibers are drawncontains approximately 60% lead oxide, 34% silica, and 6% potash.

The glass fibers formed from this lead glass by means of theabove-described mechanical drawing process, when the lead glass fibersare drawn to exceedingly small diameters of the order of a few micronsor smaller, are of very high tensile strength, are relatively fiexibleand stretchable, and have other desirable characteristics rendering themsuitable for the various conventional textile spinning and weavingoperations. This is important in preventing the finished protectivefabric from being of a relatively prohibitive cost to those groups whoare most in need of such a fabric, as the thread or filament from whichthe fabric web is to be woven must be capable of being woven byconventional mass production textile methods.

The fabric web woven from the drawn lead glass filaments or threads isvery closely woven, and 3 to 4 ply thicknesses of the finished wovenfabric employed in the tailoring of the garment. The flexibility andstrength of the finished woven fabric is such that considerable freedomof movement is permitted for the body members of the person wearing suchprotective apparel, while still providing them with a lead equivalent ofapproximately,0.l9 millimeter, this being sufficient to reduce thepercentage transmission of scattered radiant energy emissions to thebody inside the protective garment substantially below a level wheresuch emissions would be considered dangerous to health.

Erom extensive t sts run on the lead glass from which the ,glass figfinished woven lead ers were drawn, and on the glass fabric, todetermine the absorption measurements thereof relative to 2- radiationand beta radiation, a 4 ply thickness of the fabric woven from the drawnlead glass filaments was found to transmit approximately only 3.0% ofthe beta radiation relative to the amount transmitted in air, ascompared with percentage transmission measurements of 75% to 98% forvarious commercially used drawn glass cloths. Specifically, from theseries of beta radiation absorption measurements of the protectivefabric, it was determined that a single ply of the fabric had a betaradiation percentage transmission of 46% relative to transmissionthrough air, a 2 ply thickness of the fabric had a percentagetransmission of 20%, a 3 ply thickness had a percentage transmission of8.2%, and a 4 ply thickness of the fabric a percentage transmission of3.0%. Likewise, from a series of X-ray absorption measurements of theprotective fabric composed of the mechanically drawn lead fiber glass,it was determined that a single ply of the fabric had a percentagetransmission of 17.9% relative to transmission through air, a 2 plythickness of the fabric had a percentage transmission of 7.75%, and a 4ply thickness of the fabric a percentage transmission of 2.4%. Fromthese figures, it is apparent that a 3 or 4 ply garment tailored fromthe fabric woven from the drawn lead glass fibers provides substantiallycomplete protection to bodies therein from incident radiant energyemissions which would otherwise be extremely harmful to the body.

It will be apparent, therefore, that applicant has provided a novelwoven protective fabric substantially opaque to radiant energyemissions, which is capable of being readily fabricated into protectivegarments suitable for persons required to remain in areas normallysubject to large amounts of scattered radiant energy emission, which issufificiently flexible to permit substantially unrestricted movement ofthe body members of such workers, and which provides them with aprotective covering permitting transmission of such scattered radiantenergy emissions to the bodies of such persons of the order of 2.0% to5.0% relative to the transmission of such radiation through air.

The term web used throughout the foregoing description is intended toextend to woven cloths, felting, matting, and similar forms of fabricswherein the lead glass fibers may be disposed in indiscriminantlyoriented fashion as well as arranged along pre-selected axes.

It will be understood that the proportions and the ingredients asdisclosed in the preferred embodiment are merely for the purpose ofillustration, and changes and modifications may be made withoutdeparting from the spirit of the invention or the scope of the appendedclaims.

What is claimed is:

l. A protective fabric substantially opaque to X-rays and beta rayscomprising a web of lead glass fibers.

2. A protective fabric substantially opaque to X-rays and beta rayscomprising a web of woven lead glass fibers.

3. A protective fabric substantially opaque to X-rays and beta rayscomprising a flexible web of densely woven lead glass fibers.

4. A protective fabric substantially opaque to X-rays and beta rayscomprising a flexible Web of densely woven spun lead glass fibers.

5. A woven fabric substantially impenetrable by X-rays and beta rayscomprising threads of twisted and plied mechanically drawn lead glassfilaments.

6. A fabric substantially impenetrable by X rays and beta rayscomprising threads of spun glass filaments mechanically drawn from apotash-lead-silicate compound.

'7. A fabric substantially impenetrable by X- rays and beta rayscomprising a web of threads of spun glass filaments mechanically drawnfrom a potash-lead-silicate compound.

8. A fabric substantially impenetrable by X- l'ays and beta rayscomprising a web of woven threads of spun glass filaments mechanicallydrawn from a potash-lead-silicate compound.

9. A fabric substantially impenetrable by X- rays and beta rayscomprising a flexible web of woven threads of spun glass filamentsmechanically drawn from a potash-lead-silicate compound.

10. A woven fabric substantially impenetrable by X-rays and beta rayscomprising threads of twisted and plied mechanically drawn glassfilaments containing more than 50% lead oxide.

11. A woven fabric substantially impenetrable by X-rays and beta rayscomprising threads of twisted and plied mechanically drawn glassfilament containing approximately lead oxide, 34% silica, and 6% potash.

VINCENT W. ARCHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

1. A PROTECTIVE FABRIC SUBSTANTIALLY OPAQUE TO X-RAYS AND BETA RAYSCOMPRISING A WEB OF LEAD GLASS FIBERS.